The present invention relates generally to a rasp tool of the type used by an orthopedic surgeon to contour bone or the like and, more particularly, to such a rasp tool used to prepare a femur for implantation of a femoral prosthesis.
It is known to utilize a rasp tool having a handle member that is releasable relative to a cutter member, whereby the handle can be removed after the initial rasping process of the femur. Upon removal of the handle, the cutter remains lodged in the femur to enable further contouring of the proximal end of the femur, as by calcar reaming. The cutter may then be used as a provisional or trial prosthetic implant by cooperating with mating neck/collar and head/neck provisional components in order to perform a trial joint reduction. The handle is reattached to the cutter in order to extract the cutter from the femur.
Generally, prior art rasp tools in which the cutter member is releasable relative to the handle member involve a relatively complex locking mechanism that may be difficult or cumbersome for some surgeons to operate during surgery. For example, several prior art designs require that the handle move laterally relative to the cutter in order to effect disengagement. If the cutter is countersunk in the proximal end of the femur, lateral movement of the handle may be difficult.
With respect to the manner in which the surgeon must actuate the locking mechanism, known prior art rasp tools require the same positive actuation step during both engagement and disengagement of the cutter with the handle. Depending on the particular mechanism employed, the positive actuation step may include turning and tightening, or other cumbersome steps. Furthermore, many of the prior art locking mechanisms include an actuation apparatus at the handle/cutter junction. Not only does this tend to obscure the surgeon's view of the femur during normal use of the rasp tool, but it also requires the surgeon's hand to be in the vicinity of the open wound to actuate the mechanism.
The present invention is directed to overcoming the aforementioned problems associated with prior art rasp tools. Specifically, it is desired to provide a rasp tool having a simple and reliable releasable locking mechanism that minimizes the steps required for engagement and disengagement of the cutter with the handle and provides actuation of the locking mechanism at a location that is remote from the handle/cutter junction.